Sotirchos, Elias S.

Importance Myelin oligodendrocyte glycoprotein antibody–associated disease (MOGAD) lacks proven relapse-preventive therapies. While clinical trials are ongoing, safety data may be limited and approved drugs are costly. Studies of interleukin 6 receptor blocker (IL-6RB) in MOGAD are limited by small numbers and no comparative studies, contributing to low use. Objective To evaluate the impact of IL-6RB therapy on relapse rates in MOGAD and compare relapse frequency with intravenous immunoglobulin (IVIG). Design, Setting, and Participants This international, multicenter, retrospective cohort study (January 1, 2015, through December 31, 2025) included a historical IVIG-treated cohort of varying doses. The study took place across sites in North and South America (US, Canada, Mexico, Argentina, Brazil, Chile, Colombia, and Peru). Patients with MOGAD (n = 116, no excluded patients) who received at least 1 dose of an IL-6RB were included. These data were analyzed in January 2026. Exposures Tocilizumab or satralizumab. Main Outcomes and Measures Annualized relapse rate (ARR) during IL-6RB therapy, time to next relapse after treatment initiation, and adverse events. Outcomes were compared with the IVIG cohort using inverse probability of treatment weighting (IPTW) adjusted for age, sex, prior ARR, and concomitant therapies. Results A total of 116 patients with MOGAD (89% relapsing) receiving IL-6RB (tocilizumab, 104 [90%] and satralizumab, 12 [10%]) were included; overall, 60.3% were female, 39.7% were male, and 18% were younger than 18 years. The median (IQR) IL-6RB treatment follow-up was 1.4 (0.7-2.5) years and 23 relapses occurred during 241.8 person-years of IL-6RB therapy. The ARR decreased from 0.64 (95% CI, 0.58-0.70) for relapsing MOGAD before IL-6RB to 0.09 (95% CI, 0.06-0.14) during IL-6RB treatment (incidence rate ratio, 0.08; 95% CI, 0.04-0.16). Adverse events occurred in 58 patients (50%), most commonly mild infections, although 10 (9%) had severe infections. In the IVIG cohort (n = 59), 30 relapses occurred over 133.8 person-years (ARR, 0.22; 95% CI, 0.15-0.32). After IPTW, IL-6RB was associated with a lower hazard ratio (HR) than the group who underwent IVIG therapy less than 1 g/kg every 4 weeks (HR, 4.5; 95% CI, 2.0-9.8), with no significant difference vs the group who underwent IVIG 1 g/kg or more every 4 weeks (HR, 2.0; 95% CI, 0.8-4.5). Conclusions and Relevance In this multicenter observational cohort, IL-6RB use in MOGAD was associated with low relapse rates and a favorable safety profile, though severe infections occurred occasionally. Relapse rates were lower than the group who underwent IVIG less than 1 g/kg every 4 weeks but not significantly different from the group who underwent IVIG 1 g/kg or more every 4 weeks. This supports IL-6RB as a potential relapse-prevention therapy in MOGAD; the wide availability and relative affordability of tocilizumab may enable broad global use.

Abstract Objective To assess the real‐world performance of a live (LCBA) versus a fixed (FCBA) cell‐based assay for the detection of serum antibodies directed against myelin oligodendrocyte glycoprotein (MOG‐IgG) and aquaporin‐4 (AQP4‐IgG). Methods This was a retrospective study of patients evaluated at a single tertiary academic referral center, with serum testing performed clinically for AQP4‐IgG and/or MOG‐IgG by FCBA and LCBA on the same day. Additionally, frozen banked sera from the same day for patients tested only by one assay were retrieved and tested by the other assay. FCBA was performed by the Johns Hopkins Immunology Laboratory using Euroimmun kits with detection by indirect immunofluorescence (FCBA‐IF), whereas LCBA was performed by the Mayo Clinic Neuroimmunology Laboratory with detection by flow cytometry (LCBA‐FACS). Results Of 594 specimens with paired MOG‐IgG testing, 500 were negative by both assays, 33 were positive by both assays, 56 were positive exclusively by LCBA‐FACS, and 5 were only positive by FCBA‐IF. Overall, MOG‐IgG LCBA‐FACS exhibited 95.1% sensitivity and 97.7% specificity, whereas MOG‐IgG FCBA‐IF had 45.7% sensitivity and 99.8% specificity. Of 577 specimens with paired AQP4‐IgG testing, 503 were negative by both assays, 51 were positive by both assays, 21 were positive exclusively by LCBA‐FACS, and 2 were only positive by FCBA‐IF. Overall, AQP4‐IgG LCBA‐FACS exhibited 97.3% sensitivity and 100% specificity, whereas AQP4‐IgG FCBA‐IF had 71.6% sensitivity and 100% specificity. Interpretation LCBA‐FACS for both MOG‐IgG and AQP4‐IgG had markedly better sensitivity than FCBA‐IF, with similar specificity. The use of FCBA‐IF may result in underrecognition of both MOG antibody‐associated disease (MOGAD) and AQP4‐IgG seropositive neuromyelitis optica spectrum disorder (NMOSD).